Regenerative heat exchanger



June 23, 1953 Filed March 8. 1949 A. T. BowDl-:N ETAL REGENERATIVE HEATEXGHANGER 3 sheets-sheet 2 June 23, 1953 A. T, BQWDEN TAL 2,643,097

` REGENERATIVE HEAT EXCHANGER Filed March 8, 1949 3 SheetvsTSheet 3Patented June 23, 1953 2,643,097 REGENERATIVE HEAT EXCHANGER AndrewThomson Bowden, Newcastle-upon-Tyne, and Waldemar I-Iryniszak and liaulVKolb, Whit=` ley Bay, England, assignors ofYone-fourth to C. A. Parsons& Company Limited, Newcastle upon-Tyna England Application March 8,1949, S'erial No. 80,244 In Great Britain December 12, 1947 4 Claimsr(Cl. 257-6) This invention relates to combustionl turbines of all typesembracing those in which the Working fluid may be obtained from .asolid, liquid, er gaseous source, for instance, gas, oil, or coal, andwhich may be produced either internally or externally.

rlhe invention particularly relates to sealingdevices in exchangers ofthe rotary heatacculnulative type, sometimes called the regenerativetype. Such exchangers are used in combustion turbine power units fortransferring the heat between the hot gases and the compressed air beufore it is heated in the combustion. chamber.

In a heat exchanger cf this type the heat is transferred by passing thehot gases through one half of a rotating drum containing heatA transfer.surfaces and by passing the air to which, the heat is to be transferredthrough the other half of the drum. It is usual :for` the air to passthrough one half of the exchanger after delivery from the compressor andit is therefore, at a high pressure, while the gases are passed throughthe other half of the exchanger after exhausting from a turbine and are,therefore, at a loWe pressure than the air.

The object of this inventionk is to provide a` method of sealing betweenthe tvvov parts of theA exchanger as the rotating drum passes from thelow pressure gas side to the high pressure air side, and vice versa.

Referring to the accompanying diagrammatic drawings: l

Figure 1 is a longitudinal sectionalelevation of a regenerative heatexchanger of the rotating drum type;

Figure 2 is a transverse section on the line 2-'2 of Figure l. lookingin the direction of the' ar= rows; i

Figure 3 illustrates forces acting on the shoes when a chamber passesunderneath them, the yposition being one of maximum pressure;

Figure 4 is similar to FigureV 3 with the drum moved a certain distanceon, theposition being one of intermediate pressure, and

Figure 5 is similar to Figures 3 and 4 With the rum still further movedforward, the pressure being the condition of minimum pressure;

Figure 6 is a diagram showing the relationship between periodicity` onYthe horizontal' axis and, on the vertical axis force or pressure atdifferent times;

Figure 7 illustrates diagrammatically a control system for use accordingto one form of the present invention.

In carrying the invention into effect in one form by way' of' exampleand referring iirst more particularly to Figures 1 and 2, the exchangerconsists oiv an outside casinga which is. divided into two parts byseals b. There is a gas' inlet connection at c and an air outletVconnection at d; Inside this casing an annular drum c is rotated. Asecond and internal casing f is iitted inside the drum e so that theinterior space is divided into two sections byseals g in such a Way asto provide axial openings at the ends of the casings for the air inletandl gas outlet'conn'ecu tions, The drum e which is supported by meansof'ball bearings h on the inner casing fis divided into several separateaxial chambers bythe ribs The chambers are iilled with suitable heattransfer surfaces 7, such as wire gauzes, and holes are provided in theinside and outside Walls of the drum so that the gases and air can flowthrough the drum. The seals b and g, between the air and gas sides ofthe drum, consist of shoes of such a shape' that they slide on theoutside and inside surfaces of the drum, and are oi' sufficient width tocover one complete chamberpf the drum. The shoes are pressed up againstthe surface of the drum by'push rods'lc and Z to which pressure isapplied by means of flexible n'letalY tubes m and n which are iilledwith oilV or other substantially incompressible fluid. The tubes aresupported in the outsideV and'inside' casings c and f respectively.

l The tubes m and n, which are of similar construction, consist, in oneform, of thin gauge tube of approximately oval section extending overthe entire length of the shoes. The two ends`A of the tubes are tightlyclosedv in such a manner thatl the end" pieces do not affect theflexibility oi theA tube at" the position of 'theends of the shoes. Ifthe ends 'areoi a typev which are incapable oiflexbility they can beconnected to the iie'xible part of the tube by means of a bel lov/sconnection or similar flexible joint.

In the operation ci the exchanger the drum is rotated by an externalmeans'so that givenchambers ofthe drum will, at on'e'stage; becompletely covered' by the external and internal shoes bear'- ing onthedrumV surfaces;

Referring now'toFigures 3, 4 and 5 which show the forces acting on thesho'eswhensuch a cham"- ber passes underneath them, inY Figure 3 the"one rib of the chamberhas just cleared the shoes onv the high pressureside ofthe exchanger, thereby exposing the chamber to the air pressurein this side. The pressure in the chamber, therefore, rises immediatelyto the air pressure and acts on the portion of the shoes covering thechamber.

As the drum rotates, for instance until it reaches the position shown inFigure 4, the portion of the chamber subjected to the high pressure airand exerting a high force on the shoes, is decreased while the portionof the neighbouring chamber', which has been exposed to the low pressuregas, and is, therefore, exerting a low force on the shoes, isincreasing. Finally, the position shown in Figure 5 is reached in whichthe rib between these two chambers reaches the edge of the shoes on thehigh pressure side of the exchanger and no further influence is exertedon the shoes by the high pressure air. The force, P min, then acting onthe shoes, is -given by the pressure of the low pressure gases. Thiscycle is th-en repeated as each chamber passes under the shoes.

Two periods o and p are illustrated in Figure 6. The maximum pressureoccurs at the point q. Intermediate pressure is indicated by the line 1'and minimum pressure by the horizontal line s.

ln order that the shoes should provide a seal between the high pressureand low pressure parts of the exchanger, a force must be provided equalto that exerted by the air or gas pressure in the chambers under theshoes. If a constant external pressure is supplied, it would have t beequal to that necessary to counteract the greatest force P max exertedby the high pressure air, but as the pressure exerted on the shoe by theair or gases in the chambers decreased, the remainder of the constantexternal force would produce a very high friction force, so thatconsiderable power would be required to drive the drum. This inventionreduces the power required to drive the drum by inuencing the externalpressure on the shoes to correspond with that being exerted by the airor gases in the chambers passing under the shoes.

The oil tubes m and n are, to this end, connected to a suitable controlsystem and oil pressure supply, such as a pump, supplying a constantpressure to the system.

Referring to Figure 7, the control system consists of a pump q supplyingoil, at a pressure which is maintained constant by a relief valve r tonon-return valves whence the oil is divided in the flexible sealing oiltubes m and n. The oil in the tubes is also connected through orificevalves t back to the supply side of the non-return valves s.

In operation, oil of comparatively low pressure ows through thenon-return valve during the part of the cycle when the force on theshoes is smallest, that is during the period when the force is P min(Figure 5), thereby filling the oval tubes m and n andbringing the shoesinto contact with the drum e. As soon as the gas loading on the shoeincreases, the tubes m and n tend to be compressed and displace oil backinto the supply system. When the oil pressure in the tubes m and n risesabove that set according to the relief valve r, the non-return valves sclose and the oil pressure in the tubes then increases according to theapplied force on the shoes. The orifice valves t are provided for thepurpose of draining a small quantity of oil out of the system to allowfor changes in volume of the tubes due to changes in dimensions of thecasing and the drum under operating pressures and temperatures. When thenon-return valve is closed, there is a bleed through the orifice valvesfrom the tubes to the supply side of the non-return valves, and,therefore, the shoes can lift from the drum. The bleed is adjusted sothat the degree of lift is very small, and does not materially affectthe sealing properties.

We claim:

1. In a regenerative heat exchanger having an annular rotor withlongitudinal partitions dividing it into ciroularly arranged matrixholding chambers and stationary elements for defining two separatedpassages for gas iiow through the rotor, the said chambers Ibeing openfor gas flow between the said partitions both on the inner and outerperipheral surfaces of the rotor and in combination, sealing devicesbetween the said stationary elements and the inner and outer peripheralsurfaces of the rotor for sealing the two said passages from each other,each said sealing device comprising a sealing shoe for forming a sealbetween the two said passages, the sealing shoe having a rotor-engagingsurface of arcuate extent suincient to cover a complete rotor chamber,means mounting ythe shoe for radial movement toward and away from therotor, and means for holding the shoe in sealing engagement with therotor, the last said means comprising a Aflexible tube, means supportingthe tube and compressing it against the shoe for forcing the shoe towardthe rotor, and means for keeping the tube full of incompressible liquidand varying the pressure of the said liquid in accordance with variationin gas pressure against the surface of the shoe as the rotorcompartments pass the same, whereby the force exerted against the shoeby the said tube maintains a substantially constant and relatively smallsealing pressure of the shoe against the rotor.

2. The combination according to claim 1, in which the said tube is athin Walled metal tube.

3. The combination according to claim l, in which the means for keepingthe shoe filled with liquid and varying the pressure of the said liquidcomprises a source of supply of incompressible liquid undersubstantially constant pressure, a non-return valve connecting the tubeto the said source of supply and a restricted orice also connecting thetube to the said source of supply.

4. The combination according to claim 3, in which the said tube is athin walled metal tube.

ANDREW THOMSON BOWDEN. WALDEMAR HRYNISZAK PAUL KOLB.

References Cited in the iile of this patent UNITED STATES PATENTS NumberName Date 632,442 Byle et al Sept. 5, 1899 1,516,108 Ljungstrom et al.Nov. 18, 1924 1,772,210 Dale Aug. 5, 1930 1,843,252 Toensfeldt Feb. 2,1932 2,013,499 Meckenstock Sept. 3, 1935 2,224,787 Horney Dec. 10, 19402,367,174 Rankin Jan. 9, 1945 2,446,620 Swallow et al Aug. 10, 19482,480,248 Karlsson et al Aug. 30, 1949 2,483,954 Weiss Oct, 4, 1949FOREIGN PATENTS Number Country Date 543,093 Great Britain Feb. 10, 1942620,602 Great Britain Mar. 28, 1949

